This research is aimed at the application of computer-based reconstruction and processing of cardiac images obtained during ultrasonic examination. The goals of this project are the extension of two-dimensional echocardiographic techniques to the noninvasive determination of left ventricular volume and function in coronary artery disease, the more complete evaluation of the structural changes in congenital heart disease, and the development of a three-dimensional display capability. Scanning of volumetric models and human subjects has identified instabilities in the positional indicators of signals obtained during scanning. This is being corrected by design of a new shock absorbent transducer holder and modifications of scanning techniques to correct this problem. Also, new electronics are being incorporated into the laboratory system to represent small signal amplitudes more faithfully. Signal processing efforts have resulted in the design and production of a new focusing system based on the axicon principle. An automated gain technique which also has the capability to reject clutter and correct for frequency attenuation is progressing satisfactorily. Laplacian filtration has been implemented for edge enhancement without alteration of gray scale relationships. Three-dimensional modeling of the heart has progressed satisfactorily using spherical harmonic function, a global edge operator, and geodesic tesselation of space.